Printing fluid cartridges located within a printer have a predetermined amount of printing fluid contained within the cartridge. Those cartridges dispense printing fluid through a print head. A continuous ink supply system (CISS) is configured to draw printing fluid into the cartridges. This printing fluid being drawn into the cartridges is called “continuous ink”. Thus, a CISS may increase printing capacity and allow customers to use inexpensive aftermarket printing fluids for being used with a printer.